The Ljungström Air Preheater 1920

An International Historic Mechanical Engineering Landmark

June 21, 1995 Stockholm, Sweden SMR Svenska Mekanisters Riksförening American Society of Mechanical Engineers Stockholm 1920 The Ljungström Air Preheater

The inventor Fredrik Ljungström from the Ljungström Medal Historical Significance of Landmark

Throughout the history of boilers there have been many advancements in order to obtain a better performance and lower fuel consumption. However, few inventions have been as successful in saving fuel as Economic Impact of the Landmark the Ljungström Air Preheater invented by Fredrik The use of a Ljungström Air Preheater in a modern Ljungström, then Technical Director at Aktiebolaget boiler plant saves a considerable quantity of fuel - so Ljungström Ångturbin (ALÅ). The first installation much that the cost of the preheater is generally re- in a commercial boiler saved as much as 25% of the covered after only a few months. It has been esti- fuel consumption. In a modern utility boiler the mated that the total world-wide fuel savings result- Ljungström Air Preheater provides up to 20% of the ing from all Ljungström Air Preheaters which have total heat transfer in the boiler process, but the been in service is equivalent to 4,500,000,000 tonnes Ljungström Air Preheater only represents 2% of the (4,960,000,000 tons) of oil. An estimate shows that investment. the Ljungström Air Preheaters in operation annually saves about $30 Billion US. The distribution of ther- The Ljungström Air Preheater is a remarkable in- mal power capacity in which Ljungström Air vention in many ways. About 20,000 had been sup- Preheaters are installed over the world is shown in plied to all corners of the globe by 1994. It has been the table below. The estimated distribution of annual estimated that the total operating hours amassed by saving in $US can also be found in the table below: all Ljungström Air Preheaters amount to about 1,500,000,000. Continent Installed Saving capacity % $BUS/year The earliest installations of the Ljungström Air GW Africa 65 5 1.6 Preheater have been taken out of service because the North America 471 30 6.6 fact that the boiler plants have been torn down, con- South America 3 5 2 0.7 sequently the ASME International Historic Mechani- Asia 370 24 7.7 cal Engineering Landmark is placed at Tekniska CIS 216 14 3.8 Museet in Stockholm with a permanent exhibition Europe 365 23 7.6 comprising a working model earlier used for experi- Oceania 38 2 0.5 ments 1961 - 77 at Svenska Rotor Maskiner AB. TOTAL 1560 100 28.5

Landmark Contribution to Develop- ment of New World Wide Industry

The use of the Ljungström Air Preheater started in the 1920:s throughout the whole world. In the beginning the marketing of the Ljungström Air Preheater was made in close connection with ALÅ, but most of the deliveries have actually been made Figure 1. The landmarked model of the Ljungström Air through a network of licensees throughout the world. Preheater at Tekniska Museet, Stockholm. 2 Licensees 1923 Svenska Maskinverken AB, Sweden James Howden & Co., G:t Britain* Maskin & Brobyggnad, Finland 1924 Smulders, Belgium* Nebrich, Czechoslovakia Gefia, Austria 1925 Oekonomia/Ganz, Hungary* Feuerungstechnik, Germany Lammers & Maase, Germany 1926 Air Preheater Company, USA* 1927 Gadelius, Japan* Babcock & Wilcox, France* 1930 Luftvorwärmer, Germany Sulzer, Switzerland 1932 Hueck & Büren, Germany Julius Pinsch, Germany 1933 Wiesner, Czechoslovakia 1934 Kraftanlagen Heidelberg, Germany* 1935 Dano, Denmark Skoda, Czechoslovakia Witkowitz, Czechoslovakia Cegielski, Poland 1936 Simmering, Austria* 1937 Erste Brünner, Czechoslovakia* Figure 2. Principles of the Ljungström Air Preheate Ceskomoravska, Czechoslovakia 1942 Venezia, Italy* Holima, the Netherlands* Breda, Italy* 1943 Ansaldo, Italy* Ljungström Air Preheaters are used primarily in 1947 Tosi, Italy* boiler plants for preheating the combustion air. In 1949 Gefia, Genua, Italy recent years, their use has expanded to include en- 1952 Tampella, Finland ergy recovery in combination with removal of ox- 1957 Ganz, Hungary* 1958 Burmeister & Wain, Denmark ides of sulphur and nitrogen from flue gases some- 1959 Rafako, Poland* times using catalyst coated heating element plates. 1967 Stein, France* * Still licensee of SRM

Special Features and Characteristics

The Ljungström Air Preheater is a regenerative heat exchanger, and comprises a slowly rotating rotor filled with heat transfer plates. The hot and cold gas ducts are arranged so that half of the rotor is in the flue gas duct and the other half is in the primary air duct which supplies combustion air to the furnace. The hot flue gases heat the part of the rotor in their path, and as the rotor rotates, the hot section moves into the path of the combustion air and preheats it. The rotor is divided into a number of sections which pass through seals in order to prevent the flue gases Figure 3. Span of sizes for Ljungström Air Preheaters, and the combustion air from mixing. from 0.8 to over 20 m diameter (2.5 to 66 ft)

3 A rotor in a Ljungström Air Preheater may be over paper as heating elements. The first prototype 20m (66ft) in diameter and up to a couple of metres preheater was then later installed at the factory boiler (8ft) thick. The total weight of such a rotor may be at Gåshaga. up to 1,000 tonnes (1,100 tons). The flue gases normally enter the rotor at a temperature of about 350 °C (660 °F), and are cooled to about 120 °C (250 °F) in flowing through it. These temperatures may vary somewhat, depending on the type of fuel. Gas flow rates through the largest preheaters are of the order of 2 million Nm³/h (70 million standard ft³/hr) on each side, and the temperature effectiveness, the quo- tient between the temperature drop of one side and the maximal available temperature difference, is typi- cally 85%. An advantage of the Ljungström method over other methods is that the temperature of the flue gases can be reduced below the sulphuric acid dew point without causing problems. In a recuperative heat exchanger, in which the heat flows through a Figure 4. The first prototype of the Ljungström Air separating wall, the efficiency falls off rapidly if the Preheater at Gåshaga temperature is reduced below the dew point, as deposits form on the heat transfer surfaces and act as a thermal barrier. On the other hand, deposits on the surfaces of a Ljungström Air Preheater have no meas- urable effect on heat transfer performance. The first commercial installation of the Ljungström Air Preheater was made in 1922 for AB Förenade Choklad Fabrikerna (a chocolate manufacturer) on A Ljungström Air Preheater is also relatively insen- the island of Kungsholmen in Stockholm. sitive to corrosion. Any parts that do corrode away can be easily replaced at a modest cost, and leakage of air to the flue gas side is not affected by corrosion of the heat transfer plates.

Historical Development The brothers Birger and Fredrik Ljungström founded Aktiebolaget Ljungström Ångturbin (ALÅ) on Feb- ruary 29, 1908 for development of the double rotating steam turbine. The manufacture of this invention was made in Finspång at the subsidiary Svenska Turbinaktiebolaget Ljungström (STAL). ASEA took over STAL in 1916 from ALÅ, while the development and the manufacture of turbine-powered locomotives was started at Gåshaga on the island of Lidingö nearby Stockholm. During a dinner at the Operakällaren Restaurant in Stockholm, Fredrik Ljungström, who suffered from asthma, was both- ered by the dense clouds of cigar smoke and started to wonder how it might be possible to improve the ventilation without losing heat. Using his own idea from 1895 with corrugated heat exchanger elements applied in a high pressure steam boiler resulted in the idea of the regenerative heat exchanger, and the Figure 5. Report from performance measurements at Ljungström Air Preheater was born. The first tests AB Förenade Choklad Fabrikerna. (United Chocolate were performed in ALÅ’s facilities at Gåshaga with Factories)

4 Technical Data for Typical Data for today's sizes of the Coal Fired Grate Boiler Ljungström Air Preheater Data for the hand fired boiler before and after the The sizes of boilers have since then increased and installation of Ljungström Air Preheater is as fol- below typical data for a modern installation is: lows: Boiler Size (electrical output) 300 MW 500 MW Before After Fuel Coal Oil Calorific value of coal 6940 7020 Ljungström Air Preheater Size 2 x 28.5 2 x 30 Date of measurement 1922-03-20 1922-03-21 Diameter (m) 9.9 1 1.4 Fuel consumption (kg/h) 350 288 Area (m²) 73 97 Water evaporated (kg/h) 2100 2180 Height(m) 2.0 1.8 Rotation speed (rpm) 2 Average Steam Temperature (C°) 330.7 330 2 Gas flow (Nm³/h) 450 000 610 000 Average Steam Pressure (kg/m²) 9.8 9.9 Air flow (Nm³/h) 430 000 575 000 Feed water temperature (C°) 4.,5 4.5 Gas temperature in (C°) 375 375 Gas temperature in (C°) 322 Gas temperature out (C°) 120 140 Gas temperature out (C°) 330 166 Air temperature in (C°) 3 5 50 Air temperature in (C°) 40 Air temperature out (C°) 325 324 Air temperature out (C°) 238 Effectiveness, air side (%) 85.4 84.2 Effectiveness, air side (%) 70.2 Effectiveness, gas side (%) 74.9 72. 5 Effectiveness, gas side (%) 55.3 Thermal efficiency of boiler 59.3 74.3

After the first successful installations of the Ljungström Gas Heater Ljungström Air Preheater, it was introduced on the market world-wide as a means of saving fuel in boil- The growing pressure reduce emissions from boilers. This was very successful, in spite of the fact that ers has resulted in considerable interest in new ver- many boilers had to be modified to operate with the sions of the Ljungström Heat Exchanger. One of these higher combustion air temperatures. Boilers at that applications is in connection with desulphurisation. time were not normally fitted with induced draught The process involves washing the flue gases in a fans, so the fans were incorporated in the air slurry of water and limestone particles in scrubbers preheaters. A picture of this arrangement is shown in order to make the sulphur oxides to react with the on the cover. slurry. This process cools the gas down to about 50 symbol 176 \f “Symbol” \s 10C (120 symbol 176 \f Some of the steam-turbine powered locomotives “Symbol” \s 10F), The gases are then reheated so manufactured by the company were also fitted with that they have sufficient buoyancy to rise and dis- Ljungström Air Preheaters at the front in order to perse in the higher layers of the atmosphere. increase efficiency. A regenerative heat exchanger of the Ljungström type, the Ljungström Gas Heater, is highly suitable for this purpose. Gas temperatures are in the 50 - 130 °C (120 - 265 symbol l76 \f “Symbol” \s 10F) range, i.e. at a temperature at which sulphuric acid condenses on the heat exchanger surfaces. Corrosion problems are overcome by using new types of materials such as plastic for the heating elements and coat- ings of the housing by glass flake lining.

This method of recovery was first employed 1976 in Figure 6. The Ljungström locomotive with a Japan, as the Japanese were quick to introduce strict Ljungström Air Preheater mounted at the front anti-pollution legislation for their power stations. The first European installation of this type ws made in 1981 at Wilhelmshaven on the North Sea coast of Germany. Two Ljungström Gas Heaters with a diameter of 15 m (48 ft) reheat a total gas flow of 2.8 million Nm³/h (100 million standard ft³/hr).

5 tion of a Ljungström Catalyst Air Preheater for denitrification was made in 1990 at the natural gas fired Mandalay Power Station in California, USA, by SRM licensee Kraftanlagen AG, Germany.

Historical events 1895 The inventor Fredrik Ljungström is born. 1908 AB Ljungströms Ångturbin (ALÅ) is founded on Febru- ary 29. Figure 7. Erection of the Ljungström Gas Heater in 1920 Fredrik Ljungström designs the first Ljungström Air Wilhelmshaven Preheater. Tests at laboratories at Gåshaga with a paper model. The first Letter Patent is granted in Sweden. 1921 Installation of a prototype in the factory at Gåshaga, Lidingö. The result is 16% less fuel consumption - a tech- By the beginning of 1994, experience from about 80 nical breakthrough. Ljungström Gas Heaters showed that this technol- 1922 Installation in Förenade Choklad Fabrikerna, Stockholm. ogy could be regarded as technically mature. The result is 25% less fuel consumption. Installation in Holmens Bruk, Sweden. The first licences are signed with Ljungström, Gas Heaters are also used in Svenska Maskinverken, Sweden, and J. Howden, Scotland. Technical problems occur, the grate disappears and the denitrification plants, and particularly in those in- brick walls in the boiler fall down due to the increased volving catalytic reduction of the oxides of nitro- temperature in boiler preheated air. gen. Temperatures in these plants are about the same 1923 Installation in the Turbine Locomotive. A joint venture as those in air preheaters. However, a new problem ALÅ and J. Howden, Howden-Ljungström Preheaters Ltd., occurs: clogging of the preheater by the ammonium is founded with exclusive manufacturing and sales for land use within the British Empire. bisulphate formed in the reduction process. This 1925 Air Preheater Company (APC), USA, is founded - a joint problem is overcome by improved soot blowing venture between ALÅ & J. Howden, Societé de Fabrica- methods and new types of on-line water cleaning. tion d’ Appareils Ljungström, France, is founded. 1927 New design without integral fans. 1928 Luftvorwärmer GmbH, Berlin Germany, is founded for sales in whole Europe. 1933 Totally 1,000 Ljungström Air Preheaters are delivered around the world. Ljungström Catalyst Air Preheater 1934 The first Ljungström International Technical Conference it London. Another idea which is admittedly not new - SRM 1937 ALÅ makes a profit for the first time in 15 years. holds patents on it dating back to the 1950’s - but 1949 Fredrik Ljungström is awarded the James Watt Medal from which is attractive from every angle, is to employ the Institution of Mechanical Engineers, London catalytically active materials on the rotor plates of 1951 ALÅ changes name to Svenska Rotor MaskinerAB (SRM). The first idea for the multisector Ljungström Air Preheater the preheater. This allows the reduction process for was proposed by S Juhasz. the oxides of nitrogen, for example, to take place in 1956 Tests with a High Temperature Air Preheater. the air preheater itself. An advantage of this is that it 1957 Fredrik Ljungstöm is awarded the first Ljungström Medal is necessary only to replace the rotor plates and to fit in gold from SRM. the necessary additional equipment for the injection 1964 Fredrik Ljungström passes away. The first Trisector Ljungström Air Preheater. of ammonia. The alternative in many cases involves 1965 A total of 100,000 Ljungström Air Preheaters are delivered building new gas ducts and installing a stationary around the world. matrix of catalyst elements, which can be expensive 1970 Commercialisation of the Trisector Ljungström Air and difficult to accommodate in an existing boiler Preheater plant. 1976 The first Ljungström Gas Heater in service in Japan. 1990 A total of 20,000 Ljungström Air Preheaters are delivered around the world. The first installation of a commercial In order to effect the catalytic reaction on the exist- catalytic active Ljungström Air Preheater in Mandalay ing, available surface area of a preheater and to en- Power Station, California, USA for the denitrification of sure reliable operation at the temperatures involved, flue gases. the catalysts used must be very active at these tem- 1994 The Ljungström Air Preheater is designated to be the 44th ASME International Historic Mechanical Engineering peratures and must be insensitive to the pollutants Landmark. Calamus AB purchases SRM. likely to occur. This has been a very delicate technical problem to solve. The first commercial installa- 6 The History and Heritage Program est technical publishing operations, holds some 30 of the ASME technical conferences and 200 professional development courses each year and sets many industrial and The History and Heritage Landmark Program of the manufacturing standards American Society of Mechanical Engineers (ASME) began in 1971. To implement and achieve its goals ASME formed a History and Heritage Committee initially composed of mechanical engineers, histori- The American Society of Mechanical Engineers ans of technology and the curator (emeritus) of me- Daniel T. Koenig, President chanical engineering at the Smithsonian Institution. Walter W. von Nimitz, Vice President, International The Committee provides a public service by exam- Affairs ining, noting recording and acknowledging mechani- Russell J. Grady, Nordic Correspondent cal engineering achievements of particular signifi- John R. Parker, Senior Vice President, Public Affairs cance. The History and Heritage Committee is a part Erwin Fried, P.E., Vice President, Public Informa- of ASME Council on Public Affairs and Board on tion Public Information. For further information please David L. Belden, P.E., Executive Director contact Public Information, American Society of David J. Soukup, Director International Affairs Mechanical Engineers, 345 East 47 Street, NewYork, Yesh P. Singh, P.E., San Antonio Section, Chair NY 10017-2392, 1 212-705-7740.

The ASME History and Heritage Committee Designation J. Lawrence Lee, P.E., Chair Robert M. Vogel, Secretary The Ljungström Air Preheater is the 44th Interna- William DeFotis tional Historic Mechanical Engineering Landmark Burton Dicht to be designated, the 11th to be designated outside Robert B. Gaither of the United States of America. R. Michael Hunt, P.E. Since the ASME Historic Mechanical Recognition William J. Warren, P.E. Program began in 1971, 171 Historic Mechanical En- Richard S. Hartenberg, P.E., Emeritus gineering Landmark, 6 Mechanical Engineering Euan F.C. Somerscales, Emeritus Heritage Sites, and 6 Mechanical Engineering Her- Diane Kaylor, Staff Liaison itage Collections have been recognised. Each reflects its influence on society, either in its immediate lo- cale, nation-wide, or throughout the world. An ASME landmark represents a progressive step in the evolu- Svenska Mekanisters Riksförening (SMR) tion of mechanical engineering. Site designation note SMR is a Swedish society of engineers with a Mas- an event or development of clear historic importance ter of Science Degree within Mechanical, Vehicle and to mechanical engineers. Collections mark the con- Aeronautical Engineering. The aim of SMR is to pro- tributions of a number of objects with special sig- mote the technical and industrial development as well nificance to the historical development of mechani- as a good spirit among its fellows. cal engineering.

The ASME Historic Mechanical Engineering Rec- Address ognition Program illuminates our technological her- Kommendörsgatan 16 itage and encourages the preservation of the physi- P.O.Box 5164, 102 44 STOCKHOLM, SWEDEN cal remains of historically important works. It pro- Phone: +46 8 667 93 20 vides an annotated roster for engineers, students, Telefax: +46 8 667 97 05 educators, historians and travellers. It helps estab- lish persistent reminders of where we have been and where we are going along the divergent paths of dis- Officials covery. Jan-Gunnar Persson, President The 125,000-member ASME is a world-wide engi- Lars-Torsten Olsson, Vice President neering society focused on technical, educational and Mats Lindgren, Treasurer research issues. It conducts one of the world’s larg Olle Rutgerssson, Secretary 7 Acknowledgements The American Society of Mechanical Engineers also wants to thank the sponsors who financially have sup- The American Society of Mechanical Engineers is ported the ceremony and the permanent exhibition grateful to all those who have contributed to the des- at Tekniska Museet, Stockholm: ignation of the Ljungström Air Preheater as an In- ternational Historic Mechanical Engineering Land- ABB Air Preheater Inc, Wellsville, USA mark. Special thanks to Dr Stephen Juhasz who was ABB Gadelius KK, Kobe, Japan the initiator and prepared the nomination material, ABB STAL AB, Finspång, Sweden to Eugene Krumm ABB Air Preheater Inc for being Asea Brown Boveri AB, Västerås, Sweden the copreparer of the nomination material, to Dr James Howden Ltd, Glasgow, Scotland Stefan Essle, SRM for writing the commemorative Kraftanlagen AG, Heidelberg, Germany brochure, and to the Ljungström Landmark Com- Svenska Rotor Maskiner AB, Nacka, Sweden mittee: Gert Ekström, Tekniska Museet, Dr Olle Tekniska Museet, Stockholm, Sweden Ljungström, Prof Em Carl-Göran Nilson, Prof Jan- Gunnar Persson, KTH & SMR and Bo Sångfors, SRM for supplying materials and co-ordinating the ceremony.

Internationellt Historiskt Minnesmärke för Mekanisk Ingenjörskonst Ljungströms Luftförvärmare Stockholm 1920

DR. FREDRIK LJUNGSTRÖM UPPFANN DEN ROTERANDE REGENERATIVA LUFTFÖRVÄRMAREN FÖR ATT ÖKA VERKNINGSGRADEN I ÅNGPANNOR. DEN ANVÄNDEVÄRMELAGRANDE, LÅNGSAMT ROTE- RANDE, TÄTT PACKADE KORRUGERADE PLÅTAR AV STÅL FÖR ATT INDIREKT ÖVERFÖRA VÄRMET FRÅN DE VARMA AVGASERNA TILL DEN INKOMMANDE FÖRBRÄNNINGS-LUFTEN.LJUNGSTRÖMS LUFTFÖRVÄRMARE VISADE SIG VARA ENKEL, EFFEKTIV OCH TILLFÖRLITLIG. MER ÄN 20.000 HA INSTALLERATS ÖVER HELA VÄRLDEN, DE FLESTA I ÅNGKRAFTVERK OCH ÅSTADKOMMER VÄSENT LIGA BRÄNSLE-BESPARINGAR. TEKNIKEN TILLÄMPAS IDAG ÄVEN I ANLÄGGNINGAR FÖR RENING AV RÖKGASER.

SMR SVENSKA MEKANISTERS RIKSFÖRENING 1995

International Historic Mechanical Engineering Landmark Ljungstoröm Air Preheater Stockholm 1920

DR. FREDRIK LJUNGSTRÖM INVENTED THE REGENRATIVE AIR PREHEATER TO IMPROVE THE EFICIENCY OF STEAM BOILERS IT IS USED HEAT STORING SLOWLY ROTATING CLOSELY PACKED, CORUGAATED STEEL SHEETS TO TRANSFER HEAT INDIRECTLY FROM THE HOT FLUE GASES TO THE INCOMING COMBUSTION AIR THE LUNGSTRÖM AIR PREHEATER PROVED SIMPLE EFFECTIVE AND RELIABLE. MORE THAN 20,000 HAVE BEEN INSTALLED WORLD-WIDE, PRIMARILY IN STEAM-ELEC- TRIC POWER PLANTS TO PROVIDE SIGNIFICANT FUEL SAVINGS. APPLICATIONS TODAY ALSO INCLUDED ENVIRONMENTAL CONTROL

THE AMERICAN CITY OF MECHANICAL ENGINEERS 1995

H185